Improved gage for measuring the pressure of explosive gases



T. SHAW.

' Pressure Gage.

Patented May 3, 1864.

.6 w a M V/TWESSE'S amwv/gm UNITED, STATES PATENT OFFICE.

THOMAS SHAW, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO HIM- SELF AND PHILIP S. JUSTIOE.

IMPROVED GAGE FOR MEASURING THE PRESSURE OF EXPLOSIVE GASES, dc.

Specification formingpart of Letters Patent No. 12,627, dated May 3, 1864.

T0 aZZ whom, it may concern.-

Be it known that I, THOMAS SHAW, of the city and county of Philadelphia, Pennsylvania, have invented certain Improvements in Pressure-Gages. Saidimprovementsare made upon a gage patented (and owned by myself a 1d partner in these present improvements) on the 24th day of February, 1863, No. 37,794; aid I hereby declare the following to be a full, clear, and exact description of said improvements, reference being had to the accompanying drawing, and to the letters of reference marked thereon.

The object of my invention is to measure sudden pressures, more particularly the explosion of gases, &c. It is, however, as well adapted to measuring slow hydraulic pressures.

The nature of my invention consists, first, in the employment ofa gas-chamber, with suitable valve, for the purpose as hereinafter described; second,in the em ploymen'tofavalves in a faucet, for the purpose as hereinafter described third, in the employment of a metal lie disk and glycerine for the purpose of preventing the destruction of the gum, as hereinafter described.

In order to enable others to use and practice my invention, I will proceed to desciibe its construction and operation.

On reference to the accompanying; drawing, which forms a part of this specification, the drawing represents a vertical section through the center of the gage, of which A is the base, 0 an iron disk screwed into same, having on its upper side a faucet, B, of which M is the rotary plug, operated by tle handle N, and secured in the body B by the nut and washer O; Q, a brass disk secured to faucet B by screws 6 e, forming a dial in front of faucet; E, a glass tube impinging on gum ring R, and secured at its upper end by brass cap J, screwing into ring K, the latter secured to brass pipe 1), and the whole secured to board G by means of brackets F and screws H I, a brass acorn-shaped head screwed in the top of cap J and down upon a piece of gum, 9, that closes the bore of glass tube for the purpose of preventing the escape of mercury during transportation of the gage; f, an air-passage in said acorn, communicating with the bore in glass tube E on the removal of the gum g h h, the mercurychamber, communicating with the glass tube through the passage-way i; i, a valve of gum, or other suitable material, secured by screw j in the recess in plug M. Said valve covers the orifice and closes the passaget' when there is a down ward current in said passage, (which runs from the glass tube to chamber 71,) as hereinafter described.

70 is a passage way or orifice, situated at right angles with the passage-way i, for the purpose as hereinafter described P, a piston or plunger, having heads of different areas, working free, with a limited amount of stroke, in the base A. The larger head of said plunger supports the mercury-pressure in chamber h. The smaller head receives the pressure to be applied, (or to be measured,) as explained in my former patent referred to. V is a gum disk stretched across said plunger P and intervening disk 0 and base A, for the purpose of making a tightjoint.

on is a gum disk secured in position to cover the bottom of plunger P by means of metallic disk S, screwed upon the same. a n are orifices for admitting the pressure of fluid to the under side of plunger P. The top side of d sk S is recessed out for the purpose of admitting the pressure of the fluid to the whole under side of theplunger, (when operated,) as

hereinafter described. Said disk S is used for v the further purpose of supporting the gum disk m in case of a vacuum on its under side, (which, without this provision, would be torn asunder,) also for the protection of the gum from instruments, 800., when operating with the gage, as hereainfter described.

0 is an aperture for the admission of air between the two piston-heads to keep the intervenin g chamber free from pressure during any change of temperature; Y and Z, two hemispheres screwed upon hollow cup U, the upper side of which is provided with a gum or other suitable valve, a, secured in center by screw b. Said valve covers the orifices c c, the whole making a chamber for the retention of explosive gases, to operate thegage, as hereinafter described. Said chamber has upon its upper and lower end screws for attachment. The upper end is screwed into pipe W, which communicates with the gage by screwing into nut T.

X is the fluid glycerine, for the purpose as hereinafter described.

The object of valve a in chamber U is to receive and retain the gases exploded in pipe \V and chamber Y until they will have had sufiieient time to operate the mercury column 1' through plunger P, (the plunger and column being operated the same as in my former patent referred to The object of valve 2' is to support the column of mercury at the highest point to which it may ascend, (by reason of pressure applied on the under side of plunger P, as afore described.) I

The object of the cross-orifice 7c is to allow the column to fall (by giving the plug M onequarter turn) after the pressure from beneath has been removed and height of column made note of.

The object of the glycerlne X in pipe. V is to keep the gum disk m cool, and to prevent injurious chemical effect upon said gum by the explosive gases.

The principle of the other part of the gage is the same as in my patent referred to.

What I claim, and desire to secure by Letters Patent, is-- 1. The employment of a chamber, Y, when provided with a valve, a, and in combination with a gage, for the purpose specified.

2. The employment of glycerine, in combination with the gage, for the purpose specified.

3. The employment of the metallic disk S, in combination with gum disk m, for the purpose specified.

4. The employment of faucetllLiu combination with valve 6, for the purpose specified.

THOMAS SHAW. [L. s.]

Witnesses:

J. HOWARD MITCHELL, Gno. (J. MITCHELL. 

